Circuit breaker



Feb. 8, 1944. J w MAY gr AL 2,340,973

CIRCUIT BREAKER Filed llay 6, 1941 2 Sheets-Sheet 2 Mofor 80/ I65 l9/m 5&

2 BY 243 55 m7 g ATTORNEY Patented Feb. 8, 1944 CIRCUIT BREAKER John W. May,

Pittsburgh, and William H.

Stuellein, Pitcairn, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application May 6, 1941, Serial No. 392,048

13 Claims. (Cl. 200-106) This invention relates to circuit breakers and more particularly to circuit breakers of the type which are tripped instantaneously in response to overload currents above a predetermined value and after a time delay on lesser overloads.

One object of the invention is to provide a circuit breaker with an improved trip device of simple and inexpensive construction which is operable to trip the breaker instantaneously upon the occurrence of overloads above a predetermined magnitude and after a time delay for continuing overloads up to said predetermined values.

Another object of the invention is the provision of a circuit breaker having an improved ment thereof when read in conjunction with the accompanying drawings, in which:

Figure l is a vertical sectional view through the center pole of a three pole circuit breaker sucker type time delay device in which the time delay elements are self-aligning.

Another object of the invention is the provi sion of a circuit breaker having an improved time delay device including a pair of engageable elements, one of which is mounted to permit automatic alignment thereof with the other ele' ment and which is rotatable to vary the amount of time delay.

Another object of the invention is the provision of a circuit breaker having an improved trip device provided with a time delay device of the suction disc type wherein one of the discs is adjustable to adjust a magnetic air gap and the other of said discs is adjustable to vary the duration of the time delay.

Another object of the invention is the provision of a circuit breaker having an improved trip device operable instantaneously in response to overloads above a predetermined value, a time delay device to delay tripping in response to overloads below the predetermined value and adjustable means to vary the instantaneous tripping point.

Another object of the invention is the provision of a circuit breaker having a trip device provided with an improved sucker type time delay device said time delay device being removably supported on the trip device.

Another object of the invention is the provision of a circuit breaker with a trip-device having an improved calibrating and adjusting means.

The novel features that are considered char acteristic of the invention are set forth in particular in the appended claims. The invention itself. however, both as to structure and operation, together with additional objects and advantages thereof, will be best undertsood from the following detailed description of one embodiembodying the features of the invention;

Fig. 2 is a fragmentary sectional view taken substantially on the line IIII of Fig. 1;

Fig. 3 is a vertical sectional view through the trip device taken substantially on line IIIIII of Fig. 2 and showing the trip mechanism in instantaneously tripped condition;

Fig. 4 is a vertical sectional view similar to Fig. 3, but showing the trip device in condition when tripped after a time delay;

Fig. 5 is a detail view in elevation of the time delay device;

Fig. 6 is a bottom view of the upper suction disc showing the suction areas; and

Fig. 7 is a horizontal sectional view through the time delay device taken on line VII-VII of Fig. 4 and looking in the direction of the arrows. Fig. 7 shows the suction areas of the lower suction disc.

Referring to Figure 1 of the drawings, It is a operating mechanism comprises a pair of parallel frames ll (only one being shown) rigidly joined by a cross member 19 which is secured to the central portion of the base II by means of bolts 2| and 23. The frames H are also Con nected by a cross member 25 at their outer ends to form a rigid framework. The bolts 23 project through the cross member I 9 and serve as means for securing a connector 2'! of conducting material to the cross member IS.

A pivot 29 extends through a hole in the casting 21 and pivotally supports a forked contact arm M for the center pole of the breaker. The forks (only one being shown) of the contact arm 3i are disposed one on each side of the casting 21. The contact arms for the two outer poles not shown) are mechanically connected tor movement with the central contact arm 3|, as will be hereinafter described so that this central contact arm forms the common switch memher and support for the movable contacts of all three of the poles. The free end of the contactarm 3l pivotally carries a main contact 33 and an arcing contact 35 adapted to cooperate respectively with stationary contacts 39 and 31 secured to a contact member 4!. The contact member 4| is secured to the base I I by means of bolts 43, the member 4I being bent at right angles and passing through the base to form a terminal conductor 45.

The contact 33 is electrically secured on a contact member 41 pivoted on a pin 49 supported in projections (only one being shown) of the contact arm 3|. A spring 53 compressed between a spring seat on the contact arm 3| and a spring seat in the contact member 41 provides pressure for the contacts 33 and 39.

The arcing contact 35 is mounted on a contact member 55 pivoted on a pin 51 mounted in projections 59 of the contact arm. A rod GI pivotally connected to the contact member 55 slidably projects through an opening in the contact arm 3|. A spring 53 surrounding the rod BI is compressed between the contact arm 3| and a flange 65 on the rod GI to provide contact pressure for the arcing contacts 35 and 31.

The contact arms for the two outer poles of the breaker, which are disposed on opposite sides of the center pole and main frame, are mechanically connected to the center pole contact arm for movement therewith as a unit by means of a tie bar 81 which extends acrossthe three poles of the breaker. The tie bar 61 is surrounded by a sheath of insulating material 69 to insulate the several poles and is secured to each of the contact arms by means or a clamp and a bolt 1|.

The terminals, conductors, contact means and contact arms of the two outer poles (not shown) are identical in construction to the corresponding elements of the center pole except that the contact arms of the two outer poles do not have any lower forked 0r pivoted portion as in the case of the center pole contact arm, and conducting blocks of the outer poles corresponding to the center pole block 21 are bolted directly to the base II.

When the contact arm 3| is rotated clockwise, as will hereinafter be described, to open the contaots, the springs 53 and 53 rock the contact members 41 and 55, respectively, counterclockwise about their pivot pins. This movement of the contact member 41 is limited by a projection 13 thereon striking the body of the contact arm 3| and the movement of the contact member 55 about its pivot is limited by a nut on the end of the rod 6| striking the contact arm. The arrangement of the parts is such that the contacts 33-39 open before the arcing contacts -31.

The are incident to the rupture of the current is dissipated by are extinguishers 15 of which there are three, one associated with each pole of the breaker. Each of these arc extinguishers comprises, generally, a stack of slotted plates disposed adjacent the path of travel of the arc- :ng contacts 35. The plates of the extinguisher cause the arc to be drawn toward the ends of the slots and into the stack of plates resulting in the breaking up of the are into a plurality of small arcs and causes said arcs to be quickly cooled and extinguished.

The electrical circuits for the several poles of the breaker are essentially the same, each circuit extending from the terminal through the contact member 4|, contacts 33-39, the contact member 41, a flexible shunt conductor 19 connecting the contact member 41 and the casting 21, and a conductor 8| secured to said casting 21. The conductor 8| extends downwardly from the casting and is bent at right angles to project through the base II forming a terminal 83 which, together with the terminal 45, serves to connect the breaker in an electrical circuit. The circuit through the arcing contacts extends from the terminal 45 through the arcing contacts 31-35, and a flexible shunt conductor 11 to the main contact member 41 and thence through the flexible shunt conductor 19 and block 21 to the lower terminal 83.

A spring 85 having one end connected to the contact arm 3| near its free end, and its other end hooked over a fixed pivot pin 81 supported in the frame I1 biases the contact arm 3| in a clockwise direction toward open position. Under normal circuit conditions, the contact arm 3| is releasably restrained in closed circuit position (Fig. 1) by means of a linkage and toggle arrangement described as follows:

A lever 89 (Fig. l) pivotally mounted on a fixed pivot comprising a shaft 9| supported in bearings in the main frame I1, is connected by a main operating toggle comprising links 93 and 95 to the contact arm 3|. The toggle links 93 and 95 are pivotally connected by a knee pivot pin 91, and the link 95 is pivoted on a pin 99 supported in the forks of the contact arm 3|. The link 93 is pivotally connected to the lever 89 by a pivot pin IIJI.

A link I03 connects the lever 89 to one arm of a lever I05 pivoted on the fixed pivot 81. The other arm of the lever I05 is pivotally connected to one end of a toggle link I01 having its opposite end pivotally connected to a toggle link I09 by a knee pin III, the toggle link I09 being pivoted on a fixed pivot I I3 supported in the frames I1. The link 95 comprises a pair of links joined by a cross bar II5, which cooperates with an extension of the link 93 to limit upward movement of the main operating toggle. The lever 89 comprises a pair of levers rigidly jointed by a cross bar H1, and the link I03 and the lever I05, each comprises a pair of members joined by yokes substantially as illustrated. The toggle link I01 comprises a pair of links joined by a yoke II9 having a turned out portion I2I, the purpose of which will be described later. The toggle link I09 comprises a pair of links joined at their ends adjacent the fixed pivot I I3 by a cross member I23 having formed portions I25 and I21 thereon.

In the closed contact position of the contact arm 3|, the toggle 93-95 is overcenter above a line drawn through the centers of the pins 99 and IN and the toggle comprising the link 93 and the lever 89 is overcenter above a line drawn through the center of the knee pin 91 and the fixed pivot 9|, the overcenter movement of said toggles being limited by the end of the link 93 engaging the cross bar I I5 joining the links 95. In this position, the lever 89 is biased in a clockwise direction by the spring 85 but is prevented from rotation by the fact that the toggle I01-I09 is slightly overcenter to the left (Fig. l) of a line joining the centers of the fixed pivot H3 and the point of connection of the toggle link I01 and the lever I05 being restrained in this position by a spring I28 tensioned between the yoke H9 and the fixed pivot H3. The overcenter position of the toggle I81-I09 is adjustably dcstriking an member 25 termined by the formed portion I 25 adjusting screw I29 in the cross joining the frames I1.

It can be seen, therefore, that the linkage is effective in its overcenter position to maintain the contacts in closed position. The toggle I01- I09 is adapted to be moved to collapsed position to trip the breaker and cause opening of the contacts in response to overload currents by a trip device indicated generally at I38 (Fig. 1) acting through a trip rod I35. The trip device, when actuated in response to abnormal circuit conditions, is adapted to thrust the rod I35 upwardly, the upper end of said rod striking the portion I21 of the cross member I23, rocks the toggle link I09 clockwise about its fixed pivot II3 causing collapse of the toggle and linkage.

The trip rod I35 is surrounded by a shunt trip electromagnet enclosed in a casing I38 secured to the frame I1, which electromagnet may be energized by a shunt circuit or by a manually controlled switch to operate the trip rod I35 in a manner well known in the art.

When the toggle III1--I99 collapses, it permits the spring 85, acting through the contact arm 3I and the toggle 93-95, to rock the lever 89 clockwise about its pivot, which movement is transmitted through the link I93 to rock the lever I05. clockwise. The toggle 93-95 does not immediately break overcenter but travels as a unitary linkage with the contact arm 3I and the lever 89 until the movement of the contact arm 3I is arrested by the tie bar 61 striking a portion I31 of the frame structure I1. By the time knee pin 91 of the main toggle has passed below the center line 99-IOI the weight of the linkage and parts causes the main toggle to collapse and the lever 89 and linkage I03, I35, I01 and I09 to be automatically reset to their normal position as shown in Fig. 1.

As soon as the toggle 93-95 collapses the spring I28 aids in restoring the toggle I01-I99 to its overcenter position and in resetting the lever I05. link I03 and lever 89 to their normal position (Fig. 1). The toggle 93-95 remains in collapsed condition until the breaker is reelosed which may be accomplished either electrically or manually.

The contacts are reclosed either manually, or automatically. An electric motor unit indicated generally at I39 (Fig. 1), mounted on a bracket I40 secured to the main frame I1 is provided to automatically reclose the contacts. To close the contacts manually a handle I4I rotatably mounted in a frame I43 of insulating material secured to the main frame I1, is rotated in clockwise direction.

Pivotally mounted on the shaft 9I is a closing lever I45 comprising a pair of levers joined at their outer ends by a cross member land at.

their inner ends by a cross bar I49. A link II, adapted to be thrust downwardly upon clockwise closing movement of the handle MI, is notched at its lower end and engages an hour glass-shaped roller I53 pivotally mounted on the cross member I41. A roller I55 is rotatably mounted on a rod I51 supported in spaced projections I58 on the cross member I49.

The downward movement of the link I5I rocks the closing lever I45 clockwise about its pivot. At this movement the roller I55 engages the collapsed toggle 93-95 and moves this toggle to its overcenter position rotating the contact arm 3I counterclockwise against the tension of the spring 85 to close the contacts. When the handle MI is released, a spring I59 tensioned between the irame I1 and the closing lever I45 rocks said closing lever counterclockwise to normal position, thrusting the link I5I upwardly and returning the handle to its neutral position.

The circuit breaker may also be closed through the agency of the motor I39 which may be energized in a manner well known in the art.

The motor unit includes a crank disc I56 driven by the electric motor through a reduction gear. The crank disc carries a crank roller I60 which is adapted to engage the curved surface I62 of a plate I64 secured to the side of the closing lever at its outer end. When the motor is energized the crank roller I60 engages the curved surface I62 and rotates the closing lever in a clockwise direction to close the breaker after which the crank roller passes out of engagement with the surface I62 and the motor is deenergized by a suitable limit switch.

The breaker may be tripped manually by rotating the handle I4I through a small angle in a counterclockwise direction from its neutral position. A projection (not shown) on the handle mechanism, during such tripping movement, engages the previously described portion I2I of the yoke II9 to cause collapse oi the tripping toggle I91--I99 and opening of the contacts.

The construction of the circuit breaker as thus far described is substantially the same as that fully disclosed in the copending application of John W. May and Ture Lindstrom, Serial No. 391,625, filed May 3, 1941, and assigned to the assignee of the present invention.

The tripping rod I35 is also operated by any one of the trip devices I33, in response to overload conditions in the circuit controlled by the breaker, there being one trip device for each of at least two poles of the breaker. Since the trip devices are all alike only one will be described. 7

Each of the trip devices I33 (Figs. 1 to 4, inclusive) includes a laminated U-shaped magnet core IBI and a frame comprising a pair of parallel plates I63 joined at their outer ends by a yoke I65. The plates I63 are bent at right angles at their inner ends to form mounting feet I61 abutting against the magnet core IGI and bolts I69 pass through openings in the mounting feet I61, the magnet core I6I and the base II to secure the plates I63 and the magnet core IBI to the base, a spacer I1I of insulating material being provided between the magnet core and the base.

The core I6I is U-shaped and the conductor 8I is disposed between the two legs thereof. The flow of current through the conductor serves to energize the core. A trip lever comprising a pair of parallel joined levers I13 is pivotally supported on a rod I15 supported in the plates I93. At their outer ends, the trip levers I13 are joined by a yoke I11 and a pair of laminated armatures I19 is secured to the ends of the levers I13 adjacent the legs of the magnet core IEI.

Each of the yokes I11 carries an adjustable screw IBI locked in its adjusted position by a lock nut I83. Upon operation of the trip lever I13 in response to an overload in the circuit of its corresponding pole. the screw I8I strikes an arm I on a trip bar I81 rotatably mounted in a bracket I89 secured to the casing I38 (Fig. l). and rocks said trip bar in a clockwise direction (Fig. l The trip bar I81 extends transversely across all of the poles and is provided with an arm I85 for each pole. One of the arms I85 is in alignment with the trip rod I35 and upon clockwise movement of the trip bar I81, the rod is thrust upwardly to trip the breaker.

The adjusting screw I8l provides for uniiorni calibration of all trip units when there might be .a shoulder of the slight variations in the mounting of the trip devices.

The trip lever I13 is biased against tripping movement by a pair of springs I9I having their upper ends attached to the outer end of the yoke I11 and their lower ends connected to an adjustable plate I93. 2A screw I95 having a thumb nut I91 on the lower end thereof bearing against a formed over portion I99 of the yoke I95 cooperates with the plate I93 for the purpose of adjusting the tension of the springs I9I. The yoke I65 is also provided with spaced extensions 20I to the sides of which is adjustably secured a U-shaped scale plate 203 by means of screws 204 passing through elongated slots 206 in the plate 203. The spring plate I93 carries a pointer 205 projecting through a vertical slot 201 in the scale plate 203 which bears a scale indicating the tripping current values of the breaker.

The trip device I33 is overload device which provides a time delay for tripping the breaker on overloads below a predetermined value, for instance, 1000% of rated load, but which permits instantaneous tripping on overload above 1000% of normal.

This device includes a dashpot of the suction disc type removably mounted on the yoke I65 of the frame- I63" (Figs. 1, 3 and 4). A disc 209 is secured on the lower end of a rod 2 I I by means of a screw thread, and a pin 2I3 normally prevents rotation of the disc 209 on the rod. The rod 2II passes through an opening in a circular plate 2I5 secured to the yoke 55 by screw 2I1, said plate serving as a guide for the rod. The enlarged upper end 2I9 of the rod 2| I is provided with an open slot 22I engaging a rod 223 mounted on and extending between the sides of the tripping lever I13. The enlarged end 2I9 of the rod 2 is slidable in a cylinder 225 rotatably supported on the rod 223 and having its lower end formed into an inwardly extended flange 221. A spring 229 is compressed between the shoulder formed by the enlarged end 2I9 of the rod 2H and a washer 23E surrounding the rod 2I I and seated on the flange 221.

, Mounted between the plate 2i and the yoke I65 and securely held in place by the screws 2I1 is a spring disc 233 having three downwardly extending clips 235 substantially equally spaced about its periphery (see also Fig. 5). An annular gasket 231 (Figs. 3 and 4) is mounted between plate 2I5 and the spring memher 233. The spring clips 235 are formed in such a manner as to cooperate with annular projections 239 on the periphery of a cup-like dash pot 2 and firmly support the dash pot. The lower surfaces of the projection 239 are beveled and the spring clips 235 are tensioned inwardly into engagement with the beveled surfaces. The force exerted by the spring clips 235 presses pot 24I into engagement with the gasket 231 to form a seal for preventing oil leakage.

The dash pot MI is of moulded insulating 1naterial and serves to loosely support a suction disc 243. This disc has a concave bearing surface and rests on a substantially spherical projection 245 moulded integral with the bottom of the dash pot. A shoulder screw 241 in the projection 245 permits spherical movement of the suction disc 243 on the projection to provide for suction disc 209, contact with the disc 243.

The dash pot is removable by rotating it to provided with a dual bring spaces 249 (Fig. 5) between the projection 239 into alignment with the spring clips 235 and then lowering the pot. The dash pot is installed by aligning the spaces 249 with the spring clips 235, pressing it upwardly against the gasket 231 and then rotating the dash pot to engage the projections 239 with the spring clips 235.

Referring to Figures 6 and 7, the upper suction disc 209 (Fig. 6) is provided with two raised suction surfaces indicated at 25I, and the lower suction disc 243 (Fig. 7) is provided with two and 243 are in alignment; consequently the time delay is and when the suction surfaces 253 of the disc 243 are aligned with the depressed surfaces between the suction surfaces of the disc 209, the retarding suction force and consequently the time delay is substantially zero.

causes rotation of the disc disc 209.

A scale 251 on the periphery of the dash pot is calibrated to indicate 0% to 100% of overlap of the suction surfaces 25d and 253 (Figs. 6 and 7), or 0% to 100% of suction force. One of the spring clips 235 is extended downward as at 259 the adjusted position.

The dash pot 2M is filled with oil or other viscous liquid to approximately the level indicated by dotted lines (Figs. 3 and 4). normal current conditions, the suction surfaces of the discs 209 and 243 are pressed together and the oil squeezed out from between the suction surfaces by the downward force exerted by the springs I9I.

Referring now to Fig. 1, the movable parts of the trip device 533 are shown in the position ping lever E19 sharply counterclockwise to cause tripping of the breaker in the manner previously described.

the armature I19 and'the greater will be the force exerted to separate the suction discs. which results in tripping the breaker after shorter time delays as the yvalue of the overload increases. This is true up to overloads of a predetermined value, approximately 1000% of rated current. I

Upon the occurrence of an overload above the predetermined value or a short circuit, the magnetic pull is sufiiciently great to cause instan taneous tripping of the breaker. In this case, the tripping lever H3 is operated instantaneously compressing the spring 229 without waiting for the force applied on the rod 2 to break the suction between the suction discs. The parts are shown in the instantaneously tripped position in Figure 3.

The springs l9! return the tripping lever I13 to normal position as soon as the circuit is opened and the magnet l6l deenergized.

The open air gap at the armature H9 is determined by the upper sucker disc 209 engaging the disc 243. The air gap may be adjustedby re- "alignment of said separable suction member, said pot being rotatable to adjust one of the separable members to vary the time delay of the trip device. 3. A trip device for a circuit breaker includin a trip member, an electromagnet responsive to predetermined circuit conditions for operating moving the pin 2 I 3 and rotating the disc in either direction at least 180. axially on the rod 2 and consequently de- This moves the'disc 209 creases or increases the air gap depending on the direction the disc is rotated. The pin 213 is then reinserted to lock the disc in its adjusted position.

The dash pot and its connections to the tripping lever I13 may be readily removed from the trip device by removing the pin 223 and the two screws 211 when it is desired to instantaneously trip the breaker on all overloads. When the pin 223 and the screws 2i! have been removed the time delay device may be removed'by lower-- ing it, the cylinder 225 passing through the enlarged opening in the yoke I65. With the time delay device removed the open air gap at the electromagnet is adjustably determined by means of an adjusting. screw 263 (Figs. 1, 3 and 4) in the yoke I65. A lock nut265 is provided to lock the trip member, a time delay device including a reciprocably movable member operatively related to the trip member, a suction member'rigid- 1y mounted on the reciprocable, member, a second, suction member cooperating with the first suction member to delay operationv of the trip member.

and a pot in which said suctionmembers are disposed, said second suction member being mounted in said pot'for'universal tilting movement to permit automatic alignment of said second suction member with the first suction member, said not and said second 'suction'member being rotatable to vary the time delay of, the trip device.

4. A trip device fora .circuit breaker including a trip member, electromagnetic means operable in response to predetermined circuit conditions to operate the trip-member, and a time delay device operatively connected to said trip member for at times delaying operation of the trip device. said time delay device comprising a suction member movable with the trip member, a second suclion member cooperating with said first named.

. suction member, and a'pot having a bearing for the adjusting screw 263 in its adjusted position.

The circuit breaker is trip free under all conditions,.that is the contacts are capable of being opened upon operation of the trip device irre-.

spective of the position of the closing lever, since the assemblage of movable contacts will move to open position when the lever 89 is released even though the main operating toggle is prevented from collapsing by the closing lever.

Certain features disclosed but not claimed in this application are disclosed and claimed in the aforementioned copending application of John -W. May and Ture Lindstrom, Serial No. 391,625,

filed May 3, 1941.

Having described the preferred embodiment of r the invention in accordance with the patent statutes, it is to be understood. that various changes and modifications may be made in the structural details disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given a reasonably broad interpretation as the prior art permits.

We: claim as our invention:

1. A trip device for a circuit breaker including an electromagnet operable in response to predetermined circuit conditions, and a time delay device comprising separable suction members for at times delaying operation of the trip device.

one of said suction members being loosely supported to permit automatic alignment of said suction members, said loosely supported suction member being rotatable relative to the other suction member to vary the time delay of the trip device.

movably supporting said second suction membr to permit alignment of the second suction member with the first suction member, said not and said second suction member being rotatable to vary the time delay of the trip device.

5. A trip device for a circuit breaker including a trip member, electromagnetic means responsive to overload circuit conditions to operate the trip member, a member. pivoted on the trip member and movable therewith, a time delay device removably mounted on said trip device and including a pot for delaying operation of the trip memher in response to overload currents below a predetermined value, a reciprocable member operatively connected to the pot and separably engageable with the trip member, and resilient means between the pivoted member and the reciprocable member to permit instantaneous operation of the trip member in response to overload currents above said predetermined value.

6. A trip device for a circuit breaker comprising a pivoted trip member and an electromagnet for operating said trip member, a rod reciprocably movable with said trip member, retarding means for at times delaying operation of the trip member comprising a suction member rigidly attached to the rod, said suction member having segmental suction surfaces. a second suction member having segmental suction surfaces cooperating with the suction surfaces of the first suction member to retard operation of the trip member. and support means comprising a pot having a bearing for supporting said second suction member to permit movement thereof relative to said pot to align said suction members, said pot having means engaging the second suction member for rotating said suction member relative to the first suction member to vary the time delay.

'7. A trip device for a circuit breaker comprising a trip member, a spring biasing said trip member against tripping operation, and an electromagnet operable in response to'overload circuit conditions to operate the trip member, a member movable with the trip member, retarding means comprising a pair of suction members having raised suction surfaces thereon one of said suction members being mounted on said movable member, a pot having a bearing for movably supporting the other suction member to permit automatic alignment of said suction members, said pot being rotatable to adjust the suction surfaces of the suction members to vary the time delay on overloads below a predetermined value, resilient means between the movable member and the trip member to permit instantaneous operation of said trip member on overloads above the predetermined value independently of the suction members, and means to vary the minimum trip current characteristic of the trip device.

a trip member, an electromagnet responsive to abnormal circuit conditions for moving the trip member, and a time delay device including a reciprocably movable member, a suction member on said reciprocable membe and adjustable on s said member to vary the open air gap of theelectromagnet, and another suction member coopcrating with the first suction member to delay operation of the trip member, sa d other suction member being loosely mounted to permit automatic alignment with said first member and being rotatable to vary the time delay of the trip device.

9. A trip device for a circuit breaker including a trip member, means comprising a frame for supporting the trip member, means responsive to predetermined circuit conditions for operating the trip member, a time delay device comprising a unitary structure removably supported on the trip device, said time delay device including a pair of suction members, one of said suction members being operatively related with the trip member for at times delaying operations of aid trip device, a pot for movably supporting the other of said suction members, and means supported on the frame comprising a plurality of spaced sprin members disposed to engage spaced projections onthe pot to removably support said pot on the trip device.

10. A trip device for a circuit breaker including a trip member, means responsive to predetermined circuit conditions to operate the trip member, and a time delay device including a pair of suction members, a reciprocable member supporting one of said suction members, said recip- 8. A trip device for a circuit breaker including rocable member having a slot therein separably engaging the trip member, a member pivotally supported on the trip member at all times movable therewith, and a compression spring between the reciprocable member and said pivotally supported member to permit operation of the trip member independently of the reciprocable member.

11. A trip device for a circuit breaker including a trip member, electroresponsive means operable in response to predetermined overload current conditions to operate the trip member, a time delay device for at times delaying operation of the trip device in response to overloadcurrents below a predetermined value, a member pivotally supported on the trip member at all times movable therewith, a reciprocable member connected to the time delay device and separably engageable with the trip member, and a spring between the pivotally supported member and the reciprocable member, said spring acting to permit instantaneous operation of the trip device independently of the time dela device to trip the breaker in response to overload currents above a predetermined value.

12. A trip device for a circuit breaker operable ineresponse to predetermined circuit conditions, said trip device including a frame, a pivoted armature, an electromagnet for operating said armature, a movable member, a spring between said movable member and the armature biasing said armature against operation, a headed screw bearing against a portion of the frame and having a threaded portion threadedly engaging said'movable member for a-djustably moving the movable member, a pointer on the movable member, and a scale plate adjustably supported on the frame, said plate being provided with a guide slot-for the pointer.

13. A trip device tor a circuit breaker incluclQ ing a frame, an armature pivotally supported on said frame, an electromagnet for operating the armature, a time delay device comprising a dash pot operatively connected to the armature for delaying operation of the trip device in response to overload currents below a predetermined value. said dash pot being rotatably adjustable to vary the time delayed tripping point of the trip device. a movable member, a spring between said movable member and the armature biasing said armature against operation, a screw threadcdly engaging said movable member for adjustably moving the movable member to thereby adjust the tension of said spring, a pointer on the movable member, and a scale plate adjustably supported on the frame, said scale plate having a guide slot for receiving the pointer.

JOHN W. MAY. WILLIAM H. STUELLEIN. 

